1. Field of the Invention
The present invention relates to a cellular communication system. More particularly, the present invention relates to a Channel Status Information (CSI) transmission method and apparatus of a terminal in a cellular communication system.
2. Description of the Related Art
Recently, research has been conducted on the Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA) as useful schemes for high speed data transmission over a radio channel. In such multiple access schemes, the user-specific data and/or control information are mapped to time-frequency resources without overlap from each other, i.e., maintaining orthogonality, to identify the user-specific data and/or control information.
In a cellular communication system, one of the significant factors for providing high-speed wireless data service is bandwidth scalability for dynamic resource allocation. For example, a Long Term Evolution (LTE) system can support the bandwidths of 20/15/10/5/3/1.4 MHz. The carriers can provide services with at least one of the bandwidths, and the user equipment can have different capabilities such that some might support only 1.4 MHz bandwidth, and others might support up to 20 MHz bandwidth. The LTE-Advanced (LTE-A) system, aiming at achieving the requirements of the International Mobile Telecommunications-Advanced (IMT-Advanced) service, can provide broadband service by aggregating carriers up to 100 MHz.
The LTE-A system uses more bandwidth than the LTE system for high-speed data transmission. Simultaneously, the LTE-A system should be backward compatible with LTE system for supporting LTE User Equipment (UE). That is, the LTE-A system should be configured such that the LTE UEs can access the services provided by the LTE-A system. The LTE-A system supports up to 100 MHz bandwidth by aggregating two or more LTE subbands or Component Carriers (CC). The LTE-A system aggregates some component carriers and generates and transmits data per component carrier. Accordingly, the LTE transmission process can be used per component carrier to achieve the high speed data transmission of the LTE-A system.
In the LTE-A system supporting carrier aggregation, the Channel State Information (CSI) configuration information should be defined per component carrier and, in this case, the CSI transmission timings of UE for the component carriers should be guaranteed not conflict with each other so as to improve the system performance.
In order to address the above problems, there is a need to provide a CSI transmission method and apparatus of a UE in a wireless communication system supporting carrier aggregation that is capable of protecting conflict of CSI transmission timings, resulting in improvement of system performance. Also, there is a need to provide a CSI transmission method and apparatus of a UE in a wireless communication supporting carrier aggregation that is capable of compressing the CSI to be transmitted when the CSI transmission timings are overlapped unavoidably.